Method of manufacture of rubber compound



May 5, 1925. 1,536,288

A. L FREEDLANDER ET AL A v METHOD OF MANUFAGTURE OF RUBBER COMPOUND original Filed Dec. 26,1922

l l l vlllllll Patented May 5, Y rf vUNITED STATESI Par-ENTFFICE'l ABRAHAM L. FBEEDLANDEIR. WHiLIAM G. GOODWIN, OF DAYTON, OHIO, ASSIGNORS TO THE RUBBER DEVELOPm'T COMPANY, OF DAYTON, OEIO, A TRUST IST-ATI.

IE'JJBIODv OF IANUFACTUBE 0F RUBBER A I Original application med December '26, 1922, Serial No. 608,978. Divided and this A- October 27, 1923.

To all whom it may concern: f-

Be it known that we, ABRAHAM LL Firm LANDER and WILLIAM G. GOODWIN, citizens 'of the United States, residing at Dayton,v

' of Rubber'Compound, of which the following is a specification, reference being had therein to the accompanying drawing.'

i Our invention relates to a rubber commanent union with such steel articles.

pound and its method of manufacture and adaptation. This ap lication isI a' division of application Seria Number 608,97 8.'t

The object of our invention is to provide a rubber compound and the resulting article .of manufacture which, upon vulcanization will be resistent to acids, fumes, temperab ture chan es, electric and static influences, and the l' e.

It is also our object to provide from such a compound an article of manufacture that will be approximately one-third the weight of the present hard rubber com ounds known in the art, will have a strengt comarative with the strength of the hard rub- Eer known in the art and will be capable of being deformed without breaking While at the same time being ca able of a certain degree of resiliency in t e same manner that steel is resilient and is also capable of being deformed. The resulting article of manufacture and our method of roduciiig it permits of the production o? articles of the same predetermined characteristics so that uniform quality may be obtained in each article.

It is also our ob'ect to provide a compound which, when molded accordingto our process in connection with other articles such as steel, will adhere thereto and form a pei'- t will also adhere to rubberrcompounds such as hard rubber articles.

Referring to the drawings:

Figure 1 illustrates'the method used for applying a handle composed of our compound to a metal frame tennis racket.

Fig. 2 is an enlarged section of the mold l for making this typical application of our compound to a commercie use.

AW'e er application lied Serial Io. 871,256.

ished article. The compound ingredients f Smoke sheets ofvrubber, rosin oil, sul hur, ammonium bicarbonate, dehydrated e, and ethyl-idene-aniline, and gas black.

It is preferred to mix these several in eo Y diente in fifty to one hundred pound forts.

The following is a description of the method v of mixing and pre aring this com und on the basis of a one v undred pound ot.

We take the smoke sheets of rubber and u masticate them for t'y minutes according to the usual practice. In the place of the smoke sheets we may substitute fine para having the characteristic of great strength.

se ect 61 pounds and 12 It is essential that this rubber when finally made up be used before Vit is twent -four hours o d because after that time it gine to recover its resiliency.

the mill until plastic at which time they have achieved a temperature of approximately 130 to 180 Fahrenheit, the latter temperature being a proximately the safety temperature, we ad rosin oil tothe extent of 1 pound and 13 oz. This is a softenin and volatilizing agent. Wefthen add s pliur by sifting it in slowly as the rubber is emg worked on the mill. We use for this purpose 18 pounds and 6 oz. of the sulphur which is of the fineness to pass thi-ou h 300 mesh screen. The sulphur is. u for the usual purpose in compounds for romoting the vu canization. Thereafter w ile the mixing is taking place the dehydrated lime which has been ground as tine as it is possible to secure it is incorporated in the mass to the'extent of 3 ounds and 1 oz.. lThe lime yis used to toug en the compound and` accelerates the reaction between the rubber and the sulphur. We then add 1 pound and 8 oz. of as black for the purpose of giving color am? some ybody to the mixture, but this may be omitted. In the meanwhile,the ethyl-idene-ianiline has been heated in a steam jacketed kettle to ab/out the temperature of boilin water, that is to about 212 Fahrenheit. e then ithFi 3 is a section through a portion of A vconsists of the following Il oz. of such rub- 7 7 When these smoke sheets are Yworked on l Bti liti

dip this out of the kettle and incorporate 1 pound and 4 oz. thereof in the mixture in the mill. This acts as-an accelerator to the reaction `and adds tenacity to the resulting com ound.

T e last ingredient added is the ammonium bicarbonate to the extent of 4 pounds and 12 oz. This is added to give the s ongy or aerated character to the compoun It is -added last because the heat of mixing in the mill would volatilize it if added earlier in the process.

It is essential that this compound be molded and lvulcanized or blown within twelve hours after it has been mixed. The preferred practice is to mix fresh batches each day. .Y y

The temperature of the room in which it is kept and in which it has been mixed should be approximately Fahrenheit.

When it is desired to mold this compound into finished articles it is placedin a metal mold which is jacketed for receiving steam under pressure and cold water. The compound is ut in the mould and a mandrel is inserted arbout which the compound is to be moldedv or the article itself on which the com ound is to be molded may be inserted in t e mold, or both.

The mandrel is sometimes used to hold the article in osition while the compound is molded or lown.

' The term blown is used because, when the heat is applied to the mold, the compound ex ands and very great ressure is set up in t e mold during this mo din process. This results in the compound aving a orous appearance as will be seen in Fig. 3.

n preparing the mold the space between the mandrel and the article about which the compound is to be moldedis approximately half filled with the compound allowing the other half of the area for the expansion of the compound during the molding process.

In somel cases where it is desirel to have a soft rubber coating on the resulting article the mold is lined with a soft rubber sheet. lt is preferable to cement this sheet to the inside of the mold. The sheet itself is about one-sixty-ourth of an inch in thickness.

When the mold is closed the steam is turned on and the mold is kept under heat for one hundred thirty-iive minutes approximately. About one-third of this time in the beginning of the molding process the pressure of the steam is being gradually increased until it reaches a maximum of eighty pounds. The remainder of the time the steam is held at an eighty pound pressure. At the end of the period the steam is cut oi and cold Water is circulated through the mold to chill it and when it has been cooled the mold is opened, the mandrel is extracted and the finished article is thus completed.`

These times are approximately depending Lacasse upon the exact character of the resulting material desired. The time may be varie from fifty minutes to one hundred thirtyfive minutes by varying the quantity of lime and lethyl-idene-aniline. The larger the quantity of such agents the less time needed.

It will be understood that these quantities are approximate and some variation is possible.. The resulting product formed will have a porous but relatively stiff interior portion, an impervious portion adjacent said interior portion and a relatively resilient exterior portion.

Referring to the drawings showin the actual application of this process Ian use of this compound 1 is the frame of rubber or steel of a tennis racket having throat members 2 2 about which the handle is to in which the compound 11 is spread. It is usually desired to have a soft rubber coating for the compound. A rubber sheet 12 is provided for this purpose which is cemented on the inside of the mold so that when the article is blown the rubber sheet will be securely vulcanized to the exterior of the handle. A mandrel 13 is provided about which the handle is` molded. The end of the mandrel is adapted to receive the ends of the throat members to hold them in position while the compound is being blown or molded about them.

The mold is opened up after the treatment of the com ound has been effected, and then the mandre is withdrawn leaving the handle molded on the racket.

While we have shown and described certain features as constituting our invention it will be understood that parts have bee Y shown for purposes of illustration only, and that we do not desire to be limited to such details, as obvious modifications will occur to persons skilled in the art. It Will also be understood that some variation in time, temperature and quantity as well as substitution of materials of the same characteristics and reactions are contemplated.

Having thus fully described our invention, what we claim as new, and desire to secure by Letters Patent, is

1. In a method of manufacturing the here-l in described rubber compound, masticating smoke sheets of rubber approximately ifty minutes in a mill adding rosin oil, sifting in slowly finely owdered sulphur, adding finely powders lime, all at a temperature between approximately 130 to 180o Fahrenheit, lncorporating ethyl-idene-aniline previously brought to approximately 212 Fahrenheit, temperature and incorporating ammonium bicarbonate.,

"2. In a method v vof manufacturing thel mg finely powdered lime, all at a temperature between approximately 130 to 180 Fahrenheit, incorporating ethyl-idene-aniline reviously brought to approxlmately ing ammonium bicarbonate, and placing the mass in a molding chamber applying steam adually until the pressure is approximate- I; eighty pounds per square inch holding the ressure at approximately eighty pounds or two-thirds of the period and suddenly cooling the mold and the mass. 3. In a method of making herein described rubber compound, masticating smoke sheets, adding rosin oil, sifting in slowly finely powdered sulphur, adding finely powdered dehydrated lime and adding gas black, all while being masticated in a m1ll at tem erature approximately 130 to 180 Fa renheit; bringing ethyl-idene-aniline to the temperature of approximately 212 Fahrenheit and adding it to the mass; adding ammoni- .um bicarbonate and allowing the entire mass to cool to approximately Fahrenheit.

4. In a method of making herein described rubber compound, masticatmg smoke sheets,

ahrenheit temperature and incorporatadding rosin oil, sifting in slowly finely powdered sulphur, adding finely powdered deh drated lime and adding as lack, all

whi e being masticated in a mi at tem rature approximately -to 180 Fahre' eit.; bringing ethyl-idenefaniline to the tempera- .ture of approximately 212 Fahrenheit and adding it to the mass' adding ammonium bi- Y of resilient rubber, mixing smoke sheets,4

rosin oil, sulphur, and lime at ap roximately 130 to 180 Fahrenheit, ad ing ethylidene-aniline previously brought to about 212 Fahrenheit, adding ammonium bicarbonate and cooling the mass to approximately 70; lining an interior of a mold with rubber sheets which are cemented therein, placing the mass on said sheets and heating the mold under approximately eighty pounds pressure a redetermined period ralsing the heat a nelly-during theI first third of the erio In testimony w ereof, we affix our signatures.

niermannV L. FREEDLANDER. wiLLIAM G. GOODWIN.

suddenly @mangime mold i 

